Cracking the Pericellular Matrix Code: Exploring how MMP-2, -3, and -7 influence matrix breakdown and biomechanical...

Area of Science:

• Biochemistry
• Biomaterials Science
• Rheumatology

Background:

• Articular cartilage remodeling is crucial for joint health and osteoarthritis (OA) progression.
• The pericellular matrix (PCM), rich in collagen type VI and perlecan, surrounds chondrocytes and regulates cartilage homeostasis.
• Matrix metalloproteinases (MMPs) mediate cartilage matrix breakdown.

Purpose of the Study:

• To investigate the impact of MMP-2, MMP-3, and MMP-7 on the structural integrity and biomechanical properties of the pericellular matrix (PCM).

Main Methods:

• Human articular cartilage explants were treated with activated MMP-2, -3, or -7, individually and in combination.
• PCM structural integrity was assessed using immunolabeling.
• Atomic force microscopy (AFM) was employed to measure PCM biomechanical properties.

Main Results:

• All tested MMPs reduced collagen type VI integrity.
• MMP-3 and MMP-7 selectively degraded perlecan.
• Incubation with individual MMPs decreased PCM stiffness by approximately 31%; combinations showed similar reductions, except for MMP-2+MMP-7.

Conclusions:

• MMP-induced PCM alterations significantly impact cartilage biomechanics, resembling early OA.
• Specific MMPs exhibit distinct degradation patterns within the PCM.
• Interactions between MMPs, particularly MMP-2 and MMP-7, can modulate PCM stiffness reduction.